[Feature request] fluent static members for records

[Zaid-Ajaj]

Given an input record type:

namespace Shared.Requests 

[<Generator.FluentStaticMembers>]
type UpdateProduct = {
  productId: int
  name: string option
  categoryId : int option
}

I would love to have an attributes that generates the following for me:

namespace Shared.Requests

[<AutoOpen>]
module UpdateProductExtensions = 
    type UpdateRecord with 
        // create a minimal instance by providing the required fields
        static member Create(productId: int) = 
          { productId = productId; name = None; categoryId: None }  
        
       member product.WithName(name: string) = { product with name = Some name }
       member product.WithName(name: string option) = { product with name = name } 
       member product.WithCategoryId(categoryId: int) = { product with categoryId = Some categoryId }
       member product.WithCategoryId(categoryId: int option) = { product with categoryId = categoryId } 

Then one would be able to write

UpdateProduct
  .Create(productId=123)
  .WithName("Updated name")
  .WithCategoryId(None)

An option that makes the .With prefix optional would also be nice: [<Generator.FluentStaticMembers "With">]

I think this would be really useful for the Snowflaqe project. I might give this a try myself on one of the streams when time permits 😄

[7sharp9]

Could you just use the Generate.Lenses plugin?

[7sharp9]

You can also use the create function that the fields plugin creates, so you could do:
UpdateProduct.create 123 "Updated Name" None

[Zaid-Ajaj]

I need overloaded static members as extension methods, not module functions because in my use case, there are a lot of optional fields that I don't care about at first.

[7sharp9]

Makes sense. I often use statics for better option handling. Maybe this could expand to other areas too.

…

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On 21 Jul 2020, at 17:49, Zaid Ajaj ***@***.***> wrote:  I need overloaded static members as extension methods, not module functions because in my use case, there are a lot of optional fields that I don't care about at first. — You are receiving this because you commented. Reply to this email directly, view it on GitHub, or unsubscribe.

[robkuz]

@Zaid-Ajaj what about this?

type Foo =
    {
        a: int
        b: Option<int>
        c: List<string>
    }
    member this.Update(?a: int, ?b: int, ?c: List<string>) =
        let res =
            match a with
            | Some v ->
                {
                    this with a = v 
                }
            | None -> this
        let res =
            match b with
            | Some v ->
                {
                    res with b = v |> Some
                }
            | None -> this
        let res =
            match c with
            | Some v ->
                {
                    res with c = v 
                }
            | None -> this
        res
        
let x =
    {
        a = 1
        b = None
        c = []
    }
        
let y = x.Update(a = 2, c = ["foo";"bar"])